Lubrication device and image forming apparatus incorporating same

Abstract

An image forming apparatus includes an image bearer; a toner image forming unit to form a toner image on the image bearer; a transfer device to transfer the toner image from the image bearer onto a transfer medium; a cleaning device to remove untransferred toner from the image bearer; and a lubrication device including a solid lubricant, an applicator to apply lubricant scraped off from the solid lubricant to the image bearer while rotating, and an applicator driving device to rotate the applicator; and a controller to control the applicator driving device according to a predetermined variable to change a rotational frequency of the applicator during idle running of the image bearer.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 an image bearer; 
 a toner image forming unit to form a toner image on the image bearer; 
 a transfer device to transfer the toner image from the image bearer onto a transfer medium; 
 a cleaning device to remove untransferred toner from the image bearer; 
 an image bearer driving device; and 
 a lubrication device to apply lubricant to the image bearer, the lubrication device including:
 a solid lubricant, 
 an applicator to apply lubricant scraped off from the solid lubricant to the image bearer while rotating, and 
 an applicator driving device to rotate the applicator; and 
 
 a controller to control the applicator driving device according to a set variable to change a rotational frequency of the applicator during idle running of the image bearer, 
 wherein the applicator driving device and the image bearer driving device are independently controlled to adjust an amount of lubricant for a subsequent printing operation by changing the rotational frequency of the applicator. 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein the controller controls the applicator driving device according to an image area ratio of a toner image on the image bearer. 
     
     
       3. The image forming apparatus according to  claim 2 , wherein the controller controls the applicator driving device to increase the rotational frequency of the applicator as the image area ratio of the toner image on the image bearer increases. 
     
     
       4. The image forming apparatus according to  claim 1 , wherein the controller acquires the image area ratio for each of multiple unit areas on the image bearer divided in a main scanning direction, and
 the controller controls the applicator driving device according to the image area ratio of at least one of the multiple unit areas. 
 
     
     
       5. The image forming apparatus according to  claim 4 , wherein the controller controls the applicator driving device according to the image area ratio of one of the multiple unit areas having a highest image area ratio. 
     
     
       6. The image forming apparatus according to  claim 1 , further comprising a vibration detector to detect vibration of the lubrication device,
 wherein the controller controls the applicator driving device according to a vibration value detected by the vibration detector. 
 
     
     
       7. The image forming apparatus according to  claim 6 , wherein the controller controls the applicator driving device to increase the rotational frequency of the applicator as the vibration value output from the vibration detector increases. 
     
     
       8. The image forming apparatus according to  claim 1 , further comprising a driving device to drive the image bearer,
 wherein the controller acquires a current value of the driving device and controls the applicator driving device according to the current value. 
 
     
     
       9. The image forming apparatus according to  claim 8 , wherein the controller controls the applicator driving device to increase the rotational frequency of the applicator as the current value of the driving device increases. 
     
     
       10. The image forming apparatus according to  claim 1 , wherein the controller controls the applicator driving device to change the rotational frequency of the applicator according to one of a cumulative number of rotation of the applicator and a cumulative driving time of the applicator. 
     
     
       11. The image forming apparatus according to  claim 10 , wherein the controller controls the applicator driving device to increase the rotational frequency of the applicator in accordance with an increase in one of the cumulative number of rotation of the applicator and the cumulative driving time of the applicator. 
     
     
       12. The image forming apparatus according to  claim 1 , wherein the controller acquires a current value output from the applicator driving device and changes an upper limit of the rotational frequency of the applicator driving device according to the current value. 
     
     
       13. The image forming apparatus according to  claim 12 , wherein the controller controls the applicator driving device to lower an upper limit of the rotational frequency of the applicator as the current value output from the applicator driving device increases. 
     
     
       14. The image forming apparatus according to  claim 13 , wherein, when an amount of lubricant applied to the image bearer per unit time becomes insufficient due to a change in the upper limit of the rotational frequency of the applicator, the controller reduces image formation speed. 
     
     
       15. The image forming apparatus according to  claim 1 , wherein the set variable is at least one of a toner input amount and a lubrication capability. 
     
     
       16. A lubrication device comprising:
 a solid lubricant; 
 an applicator to apply lubricant scraped off from the solid lubricant to an image bearer while rotating; and 
 an applicator driving device to rotate the applicator, 
 wherein a setting of the applicator driving device is changed according to a set variable to change a rotational frequency of the applicator during idle running of the image bearer, and
 wherein the applicator driving device and an image bearer driving device are independently controlled to adjust an amount of lubricant for a subsequent printing operation by changing the rotational frequency of the applicator. 
 
 
     
     
       17. The lubrication device according to  claim 16 , wherein the set variable is at least one of a toner input amount and a lubrication capability.